Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 300758 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 358 AM EDT SAT APR 30 2016 .SYNOPSIS...
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WARM FRONTAL SHOWERS INCREASE TODAY. MORE INSTABILITY SUNDAY WITH COLD FRONT SINKING SOUTHEAST SUNDAY NIGHT. DRIER MONDAY. WAVE PASSES TO THE SOUTHEAST TUESDAY. LARGE UPPER TROUGH MAY BRING MORE COOL AND UNSETTLED WEATHER TOWARDS END OF THE WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/... A WARM FRONT WILL GRADUALLY LIFT NORTH...BRINGING SCATTERED TO NUMEROUS SHOWER WITH EMBEDDED THUNDERSTORMS THIS AFTERNOON AND EVENING. HIGH RESOLUTION MODELS ARE IN AGREEMENT WITH THE ONSET OF PCPN OVER SOUTHERN WV AND NORTHEAST KY BY 18Z SATURDAY. PRECIPITABLE WATER ABOUT 1.25 INCHES...DESCENT DEEP LAYERED SHEAR ABOUT 45 KNOTS...BUT LOW SFC CAPE WITH COMBINE TO PRODUCE MAINLY SHOWERS THROUGH TONIGHT. MODELS INDICATE H850 TEMPERATURES WILL BE AROUND 12C THROUGH THE PERIOD. TEMPERATURES WILL BE MILD DUE TO CLOUD COVER AND COOLING SHOWERS...GENERALLY IN THE LOWER 70S LOWLANDS...RANGING INTO THE LOWER 60S HIGHER ELEVATIONS. WENT CLOSER TO THE NATIONAL BLEND OF MODELS FOR TEMPERATURES THROUGH THE PERIOD. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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SHOULD HAVE A BRIEF LULL IN THE SHOWER ACTIVITY SUNDAY ACROSS THE CENTRAL TO WESTERN FORECAST AREA AFTER WARM FRONTAL PASSAGE AND BEFORE COLD FRONT APPROACHES IN THE AFTERNOON. GUIDANCE INDICATES MODEST INSTABILITY LATER SUNDAY WITH CAPE VALUES IN THE 1000 - 1500 J/KG RANGE AND HEIGHT FALLS AS SHORTWAVE APPROACHES SUNDAY EVENING WILL STEEPEN LAPSE RATES CLOSE TO 7C/KM. ALSO OF NOTE WILL BE 0-6KM SHEAR VALUES OF 40 - 50KTS...WHICH SUPPORTS ORGANIZED UPDRAFTS. BIG QUESTION WILL BE HOW MUCH SUN POKES THROUGH DURING THE DAY TO FURTHER ADD TO THE INSTABILITY...AS LOW CLOUDS MAY LINGER ACROSS MUCH OF THE AREA DUE TO THE EARLY MORNING ACTIVITY. EVEN SO WE SHOULD STILL HAVE ENOUGH FORCING WITH THE COLD FRONT TO KICK OFF SOME STRONGER THUNDERSTORMS...WITH SOME POSSIBLY CONTAINING GUSTY WINDS AND HAIL. SPC HAS EXTENDED A MARGINAL RISK AREA FOR SEVERE STORMS ACROSS THE REGION. ANY STORMS THAT DO DEVELOP WILL HAVE TO BE CAREFULLY MONITORED FOR FLASH FLOODING...ESPECIALLY AFTER THE HEAVY RAIN FROM SATURDAY NIGHT INTO SUNDAY MORNING THAT WILL PRIME THE AREA. HIGH PRESSURE AND RIDGING SHOULD GIVE US A BRIEF REPRIEVE FROM STORMY CONDITIONS ON MONDAY...HOWEVER THE PROGRESSIVE PATTERN WILL MAKE ANY BREAK IN THE ACTION SHORT LIVED AS NEXT SHORT WAVE COULD ARRIVE AS EARLY AS LATE MONDAY NIGHT INTO TUESDAY.
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&& .LONG TERM /TUESDAY THROUGH FRIDAY/...
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08Z MORNING UPDATE...ENSEMBLE AND OPERATIONAL MODELS ARE COMING INTO BETTER AGREEMENT FOR THE END OF NEXT WEEK...WITH LARGE UPPER LOW/TROUGH BECOMING ENTRENCHED OVER THE REGION. THIS PATTERN WILL LIKELY BRING COOL AND UNSETTLED CONDITIONS TO THE REGION. HAVE DECIDED TO GO AHEAD AND UPDATE THE LONG TERM FOR TEMPERATURES THU- SAT. IN THIS PATTERN...TEMPERATURES ARE LIKELY TO BE UNSEASONABLY COOL AND SOME WINTRY PRECIPITATION COULD BE POSSIBLE ACROSS THE HIGHER TERRAIN IN THE EASTERN FORECAST AREA. PREVIOUS DISCUSSION... MODELS STILL DIFFER ON WAVE CROSSING THE MIDDLE ATLANTIC STATES TUESDAY INTO WEDNESDAY...BUT THERE IS INCREASING CONSENSUS ITS MOISTURE AFFECTS AT LEAST SOUTHEASTERN PORTIONS OF THE FORECAST AREA. MODELS ALSO REMAIN A BIT OUT OF SYNC WITH A COUPLE OF NORTHERN STREAM SYSTEMS THAT CROSS MID TO LATE WEEK. THE GFS BRINGS COLD FRONTS ACROSS LATE WEDNESDAY AND THEN FRIDAY NIGHT...WHILE THE ECMWF TIMING IS EARLY THURSDAY ON THE FIRST COLD FRONT...AND THEN IT JUST CLOSES OFF A LARGE UPPER LOW THAT THEN SLOWLY LUMBERS THROUGH THE AREA AT LEAST THE END OF THE PERIOD. THE GFS IS FARTHER NORTH AND DEEPER WITH THE UPPER LOW...HENCE THE MORE DEFINED SECOND SURFACE FRONT. AS FOR THE UPPER LOWS...THIS IS A CLASSIC CASE OF DEEPER...BY ABOUT 350M...AND FARTHER NORTH VERSUS WEAKER AND FARTHER SOUTH. THE CURRENT FORECAST BRINGS FRONTS AND THE ASSOCIATED CHANCE FOR SHOWERS ACROSS WEDNESDAY AND FRIDAY NIGHTS...SIMILAR TO THE WPC DEPICTION. KEPT LOWS CLOSE TO PREVIOUS FORECAST AND A GUIDANCE BLEND. BLENDED IN GFS-BASED GUIDANCE FOR HIGHS...A LITTLE LOWER THAN PREVIOUS FORECAST FOR THE MOST PART.
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&& .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... OVERNIGHT...VFR CONDITIONS WILL PREVAIL...EXCEPT AT EKN...PKB...AND CKB THAT COULD SEE SOME MVFR/IFR FOG DURING THE PREDAWN HOURS. SATELLITE IMAGES SHOW HIGH CLOUDS CREEPING IN FROM THE SOUTH AND WEST...SHOULD GENERALLY PREVENT DENSE FOG DEVELOPMENT OVERNIGHT. A WARM FRONT LIFTS NORTH ON SATURDAY...WITH SCATTERED SHOWERS AND ISOLATED STORMS DURING THE EARLY AFTERNOON. WIDESPREAD MVFR CONDITIONS DEVELOPING AFTER 15-18Z...PARTICULARLY ACROSS THE EASTERN SLOPES OF THE HIGHER TERRAIN AND AT SITES SUCH AS KBKW AS A SOUTHEASTERLY FLOW TAKES HOLD. WV LOWLANDS MAY BE SLOWER TO DEVELOP MVFR CONDITIONS IN THE SOUTHEASTERLY DOWNSLOPING FLOW. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: CLOUD COVER COULD PREVENT FOG DEVELOPMENT TONIGHT. TIMING...COVERAGE AND DURATION OF ANY FOG OVERNIGHT TONIGHT COULD VARY. TIMING AND DEVELOPMENT OF MVFR CONDITIONS ON SATURDAY COULD VARY FROM FORECAST. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SAT 04/30/16 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY H H H H H H H H H H M M HTS CONSISTENCY H H H H H H H H H M M M BKW CONSISTENCY H H H H H H H H H M M M EKN CONSISTENCY L L L L L L L H H H H H PKB CONSISTENCY L L L L L L L M H H H H CKB CONSISTENCY L L L L L L L H H H H H AFTER 06Z SUNDAY... IFR POSSIBLE AGAIN SATURDAY NIGHT INTO SUNDAY NIGHT WITH ADDITIONAL ROUNDS OF SHOWERS AND THUNDERSTORMS..AND IN STRATUS LINGERING INTO MONDAY MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...ARJ/MPK NEAR TERM...ARJ SHORT TERM...MPK LONG TERM...TRM/MPK AVIATION...ARJ

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